A Deeper Look at The 5-HT1A Autoreceptor

[Ghost]

A Deeper Look at The 5-HT1A Autoreceptor:
G-Coupled Proteins, cAMP, PKA, and how it all effects gene expression and sensitivity of the 5-HT1A auto-receptor

By: “Ghost” + a little help from my friends

All scientific quotes in red. I will be updating this when I get new info/ opinions.

Introduction:

While many people with PSSD understand that the desensitization of the 5-HT1A Autoreceptor has many negative implications for sexual functioning, much less is known about the specific actions of G-coupled proteins, especially The 5-HT1A Autoreceptor, and how their actions could play into the response of the receptor.

Background Information:

G Protein Signaling.
https://www.youtube.com/watch?v=V_0EcUr_txk
https://www.youtube.com/watch?v=ZBSo_GFN3qI
(I recommend the second video, as it’s more in depth)
(The videos probably describe this better than I can. They have visuals. However, I will leave my description below incase it helps someone understand this.)

G-Protein Signaling Overview:

G protein Coupled Receptors (GPCR). Spans the lipid bilayer of the cell with transmembrane helices.

Three subunits of the G-protein. alpha, beta, gamma subunits. alpha and gamma are attached to membrane with lipid anchors.

When the receptor is Inactive...GDP is bound to the alpha subunit...Then after it's activated. GTP is inserted instead as an exchange. After activation, the subunits dissociate from the receptor as a result of a Conformational Change of the receptor.

Now this loose Alpha subunit can find another target protein, and regulate it’s action. This could be Could be Enzymes, or ion channels.

beta and gamma can regulate too, but for our purposes, we’ll simplify things, by only focusing on the alpha subunit.

After this messenger relays the message, GTP is hydrolyzed to GDP. Everything goes back to the way it was in the beginning.When the Ligand leaves the receptor, everything is Ready to work again.


This leads me into my second Area of prerequisite knowledge:

cAMP Signaling.

Here’s a good video describing what I will try and describe below:
https://www.youtube.com/watch?v=iGb93jCKVXs

First, we have to know what Adenylyl cyclase is. It’s a membrane bound enzyme that is activated by the GTP form of a G-protein subunit. Again, we will be just using the subunit alpha to simplify this process. Remember from before, that this Alpha subunit is released after the receptor (5ht1a in our case) is activated by an appropriate ligand (5-HT (Serotonin) in our case)).

So the alpha subunit in this case bonds to the Adenylyl cyclase...and then the adenylyl cyclase turns ATP into cAMP (Cyclic AMP). So this is a secondary messenger for the 5ht1a g-protein receptor.

The idea of a secondary messenger is very important, because it allows the one reaction at the activation site of the 5ht1a to control many things.

cAMP now can regulate further reactions...

The cAMP attach to the regulatory side of a PKA (this is a cAMP dependant protein inside of the cell), and then releases the catalytic subunits of the PKA. Now they can go after other proteins. These catalytic subunits then bind a P to Creb...then a creb binding protein enters…(not all of these steps are necessary to understanding this) Eventually, this complex (Creb+ Creb binding protein), activates transcription of genes. This transcription is necessary to replace receptors on the cell. Basically, activation of a g-coupled protein can activate the coding of a gene. In the case of PSSD, this could be very important.

Creb Levels are changed after SSRI treatment. Visual:

https://www.cnsforum.com/educationalres ... xp_antidep

Creb and it’s role with cAMP (from wikipedia sadly, but it describes it well).

“CREB (cAMP response element-binding protein)[1] is a cellular transcription factor. It binds to certain DNA sequences called cAMP response elements (CRE), thereby increasing or decreasing the transcription of the downstream genes.[2] CREB was first described in 1987 as a cAMP-responsive transcription factor regulating the somatostatin gene”


Images to show actions:

http://www.sciencedirect.com/science/ar ... 6914000848


Hypothesis:

SSRI’s ability to affect cAMP and PKA levels in the neuron could lead to PSSD, and could describe its action of disruption.

Arguement:

SSRI’s affect Immune response by indirectly altering cAMP and/ or PKA levels in the neuron. Creb gene expression changes could also be at play.

Reports of Disruption:

“everytime i get fever my pssd is gone.”-Pete Fri Jan 23, 2015 9:05 am

“For me (Post SSRI-Prozac), I don't get fevers”-SingleCell » Fri Jan 23, 2015 1:02 pm
It seems as if something that is tied into the immune response is also tied into the PSSD condition.This could be a wide variety of things, but it is known that SSRI’s altering of cAMP and/or PKA levels can suppress the immune response.

The Evidence:

“Possible mechanisms underlying the anti-proliferative and apoptotic effects of SSRIs on lymphocytes.:
B) SSRIs increase cAMP levels, thereby activating the PKA pathway; SSRIs inhibit translocation of PKC, ultimately resulting in reduced lymphocyte proliferation and/or SSRIs increase Ca2 + influx, causing reduced T cell proliferation in response to optimal mitogen concentrations.”

“cAMP has been shown to be an important regulator of immune responses by inhibition of T cell proliferation[54]. Consequently, an increase in cAMP in response to SSRIs could explain the anti-proliferative action of SSRIs on lymphocytes. At optimal concentrations of ConA, fluoxetine induced a rise in intracellular cAMP concentration”

“Citalopram similarly elevated cAMP levels in T cells stimulated with phytohemagglutinin”

“In conclusion, interference with the cAMP and phosphoinositol systems can explain some of the effects of SSRIs on lymphocytes, but the exact mechanism behind the immunomodulating effects of SSRIs remains unresolved and therefore requires further investigation.”

“Moreover, antidepressants have been shown to enhance G protein Sα migration from lipid rafts and thereby facilitate adenylyl cyclase activity and cAMP formation [64]. As a result, signal transduction post G protein-coupled receptor activation is enhanced. The observed rise in cAMP after SSRI treatment of T lymphocytes activated with mitogens as described by Edgar et al. [15] and [16] and Xia et al. [31]”\

While this theory of cAMP elevation from SSRI’s is quite convincing, researchers are not quite sure on it being the only cause of SSRI induced immune suppression.

“Another possible mechanism is the upregulation of the glucocorticoid receptor (GR). Antidepressants have been shown to increase GR expression, promote GR nuclear translocation and enhance GR function in mouse fibroblasts [66] and [67]. As glucocorticoids have strong immunosuppressive effects, it is possible that SSRIs exert their immunosuppressive effects on T lymphocytes through GR modulation.”


Either way that you read the past few quotes...One thing is certain. SSRI’s affect the immune response in some way. If PSSD is gene expression changes persisting after SSRI treatment, then this could easily still be a problem for PSSD sufferers. That’s scary to me. Colds and illnesses seem to hit me differently than before. Although haven’t had PSSD long enough to speculate too much.

Thus far, we have only studied the SSRI induced cAMP increase. Here we see more scientific proof to back this up, but PKA is also involved.

“Since cyclic adenosine monophosphate (cAMP) production is stimulated by some antidepressants, and since cAMP inhibits IFN-γ and stimulates IL-10 production, we postulate that the negative immunoregulatory effects of antidepressants result from their effects on the cAMP-dependent protein kinase A (PKA) pathway. “



The aim of the following article was to find a way to fix this problem in SSRI users.

"The aim of the present study was to determine whether the negative immunoregulatory effects of fluoxetine may be blocked by antagonists of the cAMP-dependent PKA pathway, such as, e.g., SQ 22536, an adenylate cyclase inhibitor, and Rp-8-Br-cAMPs "

“Rp-8-Br-cAMPs, 10−4, but not 10−6 M, normalized the fluoxetine-induced suppression of TNF-α production. It is concluded that the suppressant effect of fluoxetine on the IFN-γ/IL-10 production ratio is probably not related to the induction of the cAMP-dependent PKA pathway, whereas the suppressant effect on TNF-α may be related to the induction of PKA. The obtained results suggest that increased activation of the PKA-dependent pathway may constitute an important molecular basis for some (suppression of TNF-α production), but not all (suppression of IFN-γ production), negative immunoregulatory effects of fluoxetine.”

So we are left with inconclusive results. It is clear that SSRI’s affect the binding of ligands to 5ht receptors, which results in heightened levels of cellular cAMP, and we are aware that increased activation of the PKA system could possibly affect immune response.

Sources for section:

M. Maes, G. Kenis, M. Kubera, M. De Baets, H. Steinbusch, E. Bosmans “The negative immunoregulatory effects of fluoxetine in relation to the cAMP-dependent PKA pathway”

At this point I need to collaborate with others. If I can get those interested up to speed with the research I did above, then I would hope that they could join in on this conversation too… I have a lot more data, studies and information...But quite honestly it’s overwhelming. I’ve been working on this for a week or 2 now, and I feel like I’m stalling out on it. I know that some members will hop on me about how this really doesn’t provide treatment options, but instead theorizes. Tough guys. Sorry bout that. What I will give you, however, is how this above knowledge could tie into current treatments, and when we all get together on this, maybe we could find something new too.
The rest of the article is a pile of information regarding these treatments, and finishes with a thought about a theory I have played around with.


Possible treatments and how they work on these systems:
Forskolin:
http://www.ncbi.nlm.nih.gov/pubmed/22393824
Forskolin and cAMP
“The unique character of forskolin as a general direct, rapid and reversible activator of adenylyl cyclase not only underlies its wide range of pharmacological effects but also renders it as a valuable tool in the study of the role of cAMP"

Possible cAMP/ Histamine role? I know histamine is activated when there is inflammation, and your body is inflamed when you are sick.

“In the present investigation we studied the effect of adenylate cyclase stimulation by forskolin, as well as the modulatory effects of 5HT1A receptor agonists and antagonists on the production of cAMP”

“The 5HT1A agonist decreased cAMP concentration in the hippocampus of the rat. Both effects were significantly impaired by the 5HT1A antagonist WAY-100,135

"Taken together, 5HT1A receptors seem to be positively coupled to adenylate cyclase in the goldfish retina, where cAMP plays a role as a modulator of outgrowth and regeneration. The inhibitory effect of 5HT1A receptor agonists on retinal outgrowth might be mediated through the production of cAMP. The activation of other subtypes of 5HT receptors positively coupled to adenylate cyclase by the 5HT1A agonist, such as 5HT7, cannot be discarded."

I think that this article is really good...But it’s just so over my head. I can’t even understand much of what it is saying at all. But if someone gets this stuff better than me...please take a look. It’s talking about the specific actions that I want to look at...but it’s so precise. It’s something I will revisit in time when I have a better handle on this stuff...
http://www.jbc.org/content/274/23/16444.full
“activation of 5-HT1A receptors increased VIP-stimulated cAMP synthesis.”

http://www.ncbi.nlm.nih.gov/pubmed/15270025
"cAMP regulates immune responses, and modifications in cAMP signaling are involved in the pathophysiology and treatment of depression. In the present report, basal and forskolin-stimulated levels of cAMP were determined in mononuclear cells and lymphocytes from control individuals and major depression patients.
However, the simultaneous addition of a specific agonist of 5HT1A receptors, 8-hydroxy-(dipropylamino)tetralin (DPAT) and WAY-100,135 resulted in higher levels of cAMP than with the agonist alone
ncreases of cAMP levels by serotonin and 5HT1A agonist in the patient's cells; and (4) evidence of impairment in serotonergic transduction systems in immune cells during depression."







Histamine:

http://www.ebi.ac.uk/interpro/entry/IPR000503

“Activation of the H2 receptor results in physiological responses, including stimulation of suppressor T cells, decrease in neutrophil and basophil chemotaxis and activation, proliferation of lymphocytes and activity of natural killer cells”

H2 activation directly and potently increases cAMP.

curcumin:

“Curcuma longa is a major constituent of Xiaoyao-san, the traditional
Chinese medicine, which has been used to effectively manage stress and
depression-related disorders in China. As the active component of
curcuma longa, curcumin possesses many therapeutic properties.”

“Recent studies show that stress-induced damage to hippocampal
neurons may contribute to the phathophysiology of depression.”

curcumin administration (10 and 20 mg/kg, p.o.)
increased hippocampal neurogenesis in chronically stressed rats,
similar to classic antidepressant imipramine treatment (10 mg/kg,
i.p.). Our results further demonstrated that these new cells mature
and become neurons”

While this is big...THIS IS BIGGER

“In addition, curcumin significantly prevented the stress-induced decrease in 5-HT1A mRNA and
BDNF protein levels in the hippocampal subfields, two molecules
involved in hippocampal neurogenesis. These results raise the
possibility that increased cell proliferation and neuronal populations
may be a mechanism by which curcumin treatment overcomes the
stress-induced behavioral abnormalities and hippocampal neuronal
damage. Moreover, curcumin treatment, via up-regulation of 5-HT1A
receptors and BDNF, may reverse or protect hippocampal neurons from
further damage in response to chronic stress, which may underlie the
therapeutic actions of curcumin.”

My theory keeps running in circles...

Ok here’s the thought...It makes sense that cAMP is higher when you are on an SSRI...More activation of the 5ht1a means more subunits can bind to Adrenyl Cyclase...and therefore more ATP will be turned into cAMP. That’s one part of that thesis. The second part revolves around this quote: “ SSRIs have been demonstrated to interfere with the activation of the cAMP-dependent protein kinase A (PKA) pathway”...If SSRI’s are blocking that pathway...It totally makes sense! That would work as desensitization!The SSRI would be working almost like an agonist on the pre-synaptic side because it would be increasing binding, and therefore increasing cAMP activity...but eventually there would be a fuck up that would block this cAMP from connecting to the PKA, and therefore would block the secondary messenger system telling the 5ht1a to stop pumping out 5ht. it all works!...But then I saw this...”5HT1A agonist decreased cAMP concentration in the hippocampus of the rat”...fuck...Entire thesis fucked. Where do I turn from here?

Hope this created more questions than answers, I'd love some more opinions on this.

Ghost

[Ghost]

Some further proof that cAMP system may be linked into gene expression problems of PSSD. Raised cAMP levels increase CREB binding in some parts of the brain.

"Chronic administration of desipramine, fluoxetine and tranylcypromine has been shown to up-regulate the cAMP signal transduction cascade resulting in increased expression and function of the transcription factor CRE binding protein (CREB), in various regions of the brain, particularly the cerebral cortex and hippocampus. In turn, enhanced CREB expression leads to an upregulation in cAMP response element (CRE )-mediated gene transcription in these areas. For example, brain-derived neurotrophic factor (BDNF) expression is increased in the hippocampus."


https://www.cnsforum.com/educationalres ... xp_antidep

[hashim]

so based on all of this , cAMP is activated more so i n some regions but worse or less in others?
Here a quote of forskolin from wiki...

Forskolin (also called Coleonol) is a labdane diterpene that is produced by the Indian Coleus plant (Coleus forskohlii). Forskolin is commonly used to raise levels of cyclic AMP (cAMP) in the study and research of cell physiology. Forskolin activates the enzyme adenylyl cyclase and increases intracellular levels of cAMP. cAMP is an important second messenger necessary for the proper biological response of cells to hormones and other extracellular signals. It is required for cell communication in the hypothalamus/pituitary gland axis and for the feedback control of hormones.[2] Cyclic AMP acts by activating cAMP-sensitive pathways such as protein kinase A and Epac.

[hashim]

that histamine h2 receptor also rp is promoting erections.
http://www.ncbi.nlm.nih.gov/pubmed/7850330

These results indicate that histamine may play a role in human penile erection. The erection-promoting action of histamine is probably due to H2 receptor activation, although another histamine receptor, possibly H3, also seems to be involved. This study suggests that histamine could be a valuable tool in the diagnosis of erectile dysfunction.

[Ghost]

just sometimes get a dry cough in winter.

I've had one for the past 2 weeks plus. I don't like blaming things on PSSD without real cause, but this is something kinda new for me.

and no problem, I enjoy working on this. I want to help people.

[Ghost]

so based on all of this , cAMP is activated more so i n some regions but worse or less in others?
Here a quote of forskolin from wiki...

Forskolin (also called Coleonol) is a labdane diterpene that is produced by the Indian Coleus plant (Coleus forskohlii). Forskolin is commonly used to raise levels of cyclic AMP (cAMP) in the study and research of cell physiology. Forskolin activates the enzyme adenylyl cyclase and increases intracellular levels of cAMP. cAMP is an important second messenger necessary for the proper biological response of cells to hormones and other extracellular signals. It is required for cell communication in the hypothalamus/pituitary gland axis and for the feedback control of hormones.[2] Cyclic AMP acts by activating cAMP-sensitive pathways such as protein kinase A and Epac.

Yea my original thought is that increased 5ht1a activation would increase cAMP, because you're binding more 5ht, so that adrenyl cyclase is pumping out more cAMP. Maybe the body sees that and tries to down-regulate Ralphe Nuclei's ability to turn that cAMP into a secondary messenger system. It would describe the apparent desensitization after you discontinue...cAMP would decrease because of less activation to the 5ht1a...and if the PKA/ cAMP system is still fucked, you're getting less messages to inhibit release, and less messages to use creb to code for more 5ht1a receptors. So...you're releasing more serotonin, and you now have less 5ht1a autoreceptors...

If Forskolin activated adenylyl cyclase, and therefore increased cAMP levels...maybe you're overriding the desensitized system. That maybe could be it's action of helping.

Totally speculative, but it more or less follows what I have above in scientific data. Just a theory. But nonetheless, I want people to read it as just a theory, and not something I am sure of.

[Moloch]

Great stuff Ghost. I think I speak for everyone in saying we greatly appreciate your research efforts.

[username]

There was this one morning it felt like my sexual urges were a lot better. I had been walking outside the evening before that with too light clothing. I remember thinking about what would've caused the heightening of my libido in the morning and thought about things I did differently. There was the walk outside and I had drank some tea. I thought the walk might've helped because it's physical activity but I had done much more challenging workout other days that didn't do the same. I think it makes sense it was connected to catching cold.

I also want to say it personally that I really appreciate your efforts too.

[Ghost]

Great stuff Ghost. I think I speak for everyone in saying we greatly appreciate your research efforts.

Thank you Moloch and Username. It means a lot.

Username,

Did you catch a cold after being outside that night? I think that this could have played in somehow, if we take into account that some parts of the immune system's activity is tied into the same functions disrupted by PSSD. I think at this point I'm going to approach some experts in the field of cAMP and PKA. I feel like it's something that could be pretty important, or at least another indicator of something that has gone wrong after SSRI treatment. I just don't have the background to dig much deeper into this without the help of such a person.

The next thing I want to do is try and connect other PSSD treatments that have worked to this system of PKA/ cAMP etc... I want to figure out if the desensitization causes these disruptions, or if these disruptions cause the desensitization. Those would be 2 very different things.

Just curious, what kind of tea was it if you remember?

[Ghost]

Some people have claimed that licorice root has cured them of PSSD.

I found a connection between cAMP and Licorice Root.

"Isoliquiritigenin, glabridin, licoarylcoumarin and licoricidin were identified as strong inhibitors of adenosine 3',5'-cyclic monophosphate (cAMP) "

"In 4-arylcoumarins, 5,7-dihydroxy derivatives were generally highly inhibitory towards cAMP phosphodiesterase."

http://www.ncbi.nlm.nih.gov/pubmed/1654220

Here is how I would speculate that could help: If the cAMP system is desensitized, lowering of cAMP levels from licorice root may long term re-sensitize the system. Just a possibility.

If that were the case, things would get worse before they'd get better...I didn't find an example of it getting better, but instead of it getting worse the first day trying it.

"My genitals feel extremely cold and lifeless.
Even my feet have the numb, cold feeling."

I don't know...just a thought.